The present invention relates to a stereo microscope having a first and a second main beam path, the spacing of which defines a stereo base, while extending through the middle of the stereo base, parallel to the main beam paths, is a microscope axis, and having an optical beam splitter device for producing an assistant beam path and a documentation beam path.
Stereo microscopes of this kind are used particularly in opthalmological and neurosurgical operations. In such cases a binocular tube is provided downstream of the beam splitter device, and through this the surgeon or main operator can observe the object stereoscopically. Stereo microscopes of this kind may be of a telescope type (Galileo system) where a main objective common to both main beam paths is mounted on the microscope body. Stereo microscopes of the Greenough type are also known, in which one objective is provided for each main beam path. Often, a magnification changer or a zoom system is provided downstream of the objective. In this way it is possible to achieve different fixed magnifications or a continuous magnification range. One channel of a magnification changer (zoom system) is provided for each of the two channels (main beam path) of the stereo microscope, while the two magnification changer/zoom system channels are to be adjusted or moved in synchronism. In a structure of this kind, the above mentioned beam splitter device is expediently mounted downstream of the magnification changer/zoom system. Stereo microscopes of this kind are sufficiently well known and need not therefore be discussed in detail at this point.
When a stereo microscope of this kind is used as a surgical microscope, an assistant beam path is frequently coupled out (blanked out) from one of the two or from both main beam paths and deflected to an interface for an assistant tube, and the assistant or co-observer is able to view an image of the object through this assistant tube. When the assistant beam path is coupled out from only one of the two main beam paths, a monoscopic (non-three dimensional) image is obtained. However, in the assistant tube, an assistant beam path of this kind can be split into two channels (of smaller stereo base), thus producing a stereoscopic image with a reduced three dimensional impression. Furthermore, it is expedient and known to couple out a documentation beam path which is fed to a documentation module or documentation device. These documentation modules may be, for example, opto-electrical receivers (CCD arrays) or other image memories which are able to receive and store sequences of images or individual images. By means of documentation devices of this kind it is possible, for example, to determine the progress of an operation for documentation purposes or to store individual images of the object for later analysis.
It should be pointed out in this connection that the terms “assistant beam path” and “documentation beam path” have been chosen purely for an easier understanding of the use of the stereo microscope according to the present invention and may be replaced by the general terms “secondary beam path” or “tertiary beam path”, if these beam paths are to be used in some other way. In the description that follows, for the sake of simplicity, the terms assistant and documentation beam paths will be used without restricting the invention to a stereo microscope having corresponding assistant or documentation modules.
In the surgical microscopes mentioned above it is desirable to place the assistant or co-observer on the left or right hand side of the microscope, as desired. For this purpose, it is known to couple out an assistant beam path from the left and also from the right main beam path and lead it to a corresponding interface on the microscope housing. However, if the corresponding microscope is equipped with only one assistant tube, this tube has to be transferred from one side to the other if there is a change of assistant. Such modification is a source of risks and sterility problems. The provision of two fixed assistant tubes would be an adverse step for reasons of weight and cost.
There are also solutions in which the assistant tube is constructed to be pivotable in a horizontal plane. The horizontal plane here is a plane which is perpendicular to the plane containing the two main beam paths of the stereo microscope. These solutions require two additional assistant main beam paths extending parallel to the two stereo main beam paths, resulting in a complex four-beam microscope construction. A further disadvantage of such solutions is that the main observer tube has to be removed or at least moved out of the way before the assistant tube can be pivoted.
From EP 1486813A1, a stereo surgical microscope with an assistant tube is known which is pivotably mounted on the rear side of the microscope in a plane parallel to the stereo main beam paths. The main observer tube is arranged on the front of the microscope. The assistant tube leads backwards and outwards from the rear of the microscope and depending on the desired position of the assistant it can be pivoted from the left hand side to the right and back again. The output coupling of a documentation beam path is not discussed here. In an arrangement of this kind, for reasons of stability, it is advantageous to mount a counterweight on the pivotable assistant tube. This has proved disadvantageous in practice, however, for reasons of cost, weight and adjustment.
From D E 19504427 B4, a stereo microscope is known having a single optic, i.e. with only one channel, in which a beam splitter element is provided downstream of the main objective and a magnification changer. The beam splitter element couples a secondary observation beam path out from the primary observation beam path. The beam splitter element consists of three separate prisms. Downstream of the beam splitter element are provided two optical elements arranged adjacent to one another which provide an intermediate image of the object under consideration, detected by two opto-electronic picture receivers. A construction of this kind is suitable for a video stereo microscope. The secondary observation beam path is also imaged on a picture receiver of this kind. The entire optics of the secondary observation beam path including the beam splitter element are mounted to be rotatable about a rotation axis which extends through the pupil used jointly by the primary and secondary observation beam path. This proposed construction is unsuitable for a two-beam stereo microscope. The beam splitter element here rotates about a correspondingly broad channel of the main beam path. Moreover, this specification does not discuss the output coupling of a further tertiary or documentation beam path.
Finally, from U.S. Pat. No. 5,552,929, a stereo microscope is known having a main observer tube, a co-observer tube and a documentation output. This is also a so-called “single optical system” in which the splitting into two beam paths takes place for the first time in the tube. The output coupling of the beam paths into one beam path for the main and co-observer is carried out by means of beam splitters arranged in a correspondingly broad channel of the main beam path. The construction proposed therein is unsuitable for two-beam stereo microscopes as any pivoting of a tube in such microscopes would cause the image to rotate as well. Consequently, prisms again have to be provided which will turn the image back again. A similar system, albeit without a documentation output, is known from EP 0363762B1.
In other known two-beam stereo microscopes, hitherto a so-called “semi-” stereo assistant has been attached to the side of the beam splitter. The latter is not pivotable as the (video) documentation is already connected on the opposite side, to which the second main beam path is fed. The impossibility of changing the assistant is highly disadvantageous for users in this case. Other solutions already mentioned use a four-beam microscope structure resulting in stereo microscopes in a substantially higher price bracket.
EP 1308766B1 relates to an operating stereo microscope with two first beam splitters in the two main beam paths which couple out part of the observation beam path to video cameras which are viewed to the left and right of the main observer. Using beam deflector elements, a further part of the light of the observation beam path is guided to a main observer tube, whilst the other part is guided to a co-observer tube arranged opposite the main observer tube. In order to afford the assistant the possibility of looking into the microscope to the side (i.e. to the left or right) of the main observer, a reflection device which is rotatable through 90° is provided, which deflects the assistant beam path accordingly. In this case, the only one documentation connection is then located opposite the assistant and to the side of the main observer.
From DE 10157613A1, different arrangements of a surgical microscope are disclosed, in which either the co-observer is positioned opposite the main observer, in which case the co-observer sees a stereoscopic image, or the co-observer is positioned to the side of the main observer, in which case the co-observer views the microscopic image in monoscopy. Beam paths for a documentation device are not envisaged here.
Moreover, a stereo microscope having a beam splitter device of the kind described herein before is known from the German Patent Application DE 102006050846.7 by the present Applicant, entitled “Stereo Microscope With Beam Splitter Device”, which was filed before the filing date but had not yet been published on the filing date of the present application. In this prior application, in a first position of the beam splitter device, the assistant beam path can be coupled out of the first main beam path and in a second position can be coupled out of the second main beam path and the documentation beam path can be coupled out of the other main beam path in each case. The direction of the assistant beam path in the first position of the beam splitter device to the direction of the assistant beam path in the second position of the beam splitter device is rotated through 180° and the coupled out documentation beam path in both positions of the beam splitter device is perpendicular to the coupled out assistant beam path. By comparison with the subject-matter of the earlier application, the present application seeks to manage with a lower number of movable elements, thereby simplifying manufacture and assembly and consequently reducing costs.